Preparation method of high-density flexible tactile sensor array and application thereof

Abstract

The application provides a preparation method of a high-density flexible tactile sensor array and application thereof, and belongs to the technical field of sensing, and the preparation method comprises the following steps: mixing and stirring different Ecoflex silicon rubbers; mixing and stirring graphite and the mixed and stirred Ecoflex silicon rubbers to form a uniform composite graphite slurry; arranging the composite graphite slurry between two substrates; extruding the two substrates towards the middle, and heating and curing the extruded graphite slurry to obtain a composite film; segmenting an ITO conductive film to obtain an ITO electrode; wherein the ITO electrode is arranged on a flexible substrate; adhering the ITO electrode on the upper and lower surfaces of the composite film; and leading out a wire from the ITO electrode to obtain the high-density flexible tactile sensor array. Through the technical scheme, the tactile sensing function with high density, high flexibility and high stability can be realized.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and more specifically, to a method for fabricating a high-density flexible tactile sensor array and its application in the field of tactile perception. Specifically, it relates to a Graphite / Ecoflex composite thin film and its fabrication method, as well as the fabrication of a 16×16 ITO electrode array. Background Technology

[0002] With the rapid iteration of artificial intelligence, robotics, and wearable devices, the flexibility, high density, and high performance of tactile sensing devices have become core demands for industry development. Flexible tactile sensors, as core components simulating the tactile function of human skin, can accurately convert mechanical signals such as pressure and strain into electrical signals, playing an irreplaceable role in key scenarios such as precision operation of intelligent robots, wearable health monitoring, and tactile feedback in bionic prosthetics. However, existing flexible tactile sensor arrays suffer from problems such as low density, insufficient flexibility, poor interface compatibility, and limited application scenarios. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a method for fabricating a high-density flexible tactile sensor array and its tactile sensing applications, achieving a response to external pressure and applicable to pressure distribution detection. This invention uses ITO / PET (indium tin oxide / polyethylene terephthalate) as the flexible substrate and electrodes to fabricate a Graphite / Ecoflex composite film. By optimizing the material ratio, process parameters, and device structure, high-density, high-flexibility, and high-stability tactile sensing functionality is achieved.

[0004] To achieve the above objectives, the present invention proposes a high-density flexible tactile sensor array, comprising: A composite film, wherein the composite film contains graphite and Ecoflex silicone rubber; The composite film has ITO electrodes on both its upper and lower surfaces, and the ITO electrodes are different units divided by the ITO conductive film with a flexible substrate.

[0005] Optionally, the ITO electrodes are arranged in an array.

[0006] Optionally, the ITO electrode is connected to a corresponding wire, through which a sensing signal is output.

[0007] On the other hand, the present invention also provides a method for fabricating a high-density flexible tactile sensor array, comprising: Mix and stir different types of Ecoflex silicone rubber; Graphite and Ecoflex silicone rubber were mixed and stirred to form a uniform composite graphite slurry. A composite graphite paste is placed between two substrates; Two substrates are pressed together and the extruded graphite slurry is heated and cured to obtain a composite film. The ITO conductive film is segmented to obtain ITO electrodes; wherein the ITO electrodes are disposed on a flexible substrate. The ITO electrodes are bonded to the upper and lower surfaces of the composite film; A high-density flexible tactile sensor array is fabricated by leading wires out from the ITO electrode.

[0008] Optionally, the substrate is a substrate comprising a non-flat surface with a regular or irregular shape, and the non-flat surface of the substrate is in contact with the composite graphite slurry.

[0009] Optionally, the flexible substrate is a PET substrate.

[0010] Optionally, the process of pressing the two substrates towards the middle includes: The substrate and the composite graphite slurry are used as an assembly, and the composite graphite slurry between the assemblies is squeezed by horizontal movement of a scraper.

[0011] Optionally, the mass ratio of graphite to the mixed and stirred Ecoflex silicone rubber is 50%.

[0012] Optionally, the fabrication method of the ITO electrode includes: Obtain the electrode pattern; perform laser etching on the ITO conductive film according to the electrode pattern to obtain the ITO electrode.

[0013] On the other hand, the present invention also provides an application of a high-density flexible tactile sensor array, which applies external pressure to the high-density flexible tactile sensor array to detect the distribution of the applied external pressure.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The high-density flexible tactile sensor array prepared in this invention can be used for pressure distribution visualization and detection, and to respond to external pressure. Therefore, it can be applied to scenarios such as insole pressure detection, seat pressure distribution analysis, industrial machinery contact pressure monitoring, and precision robot operation. Furthermore, this high-density flexible tactile sensor array features high-density sensing, high flexibility, good biocompatibility, and lightweight comfort, thereby reducing the feeling of constraint and discomfort during use. The sensor achieves signal conversion based on the piezoresistive effect of the Graphite / Ecoflex composite sensitive layer, a mature and reliable sensing mechanism that can be manufactured using existing manufacturing technologies and equipment, thus improving the convenience and economy of sensor manufacturing. Attached Figure Description

[0015] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the drawings: Figure 1 This is a flowchart illustrating the fabrication process of the high-density flexible tactile sensor array of the present invention. Figure 2 A physical image and a schematic diagram of the 16×16 ITO electrode array prepared according to the present invention; Figure 3 The current response diagrams of the sensor array using Graphite / Ecoflex composite films with different mass fractions under different pressures are shown in the embodiments of the present invention. Figure 4 This is a visualization interface diagram of the pressure distribution of the sensor array in an embodiment of the present invention. Detailed Implementation

[0016] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0017] This invention belongs to the field of flexible electronic sensor technology, specifically relating to a method for fabricating a high-density flexible tactile sensor array and its tactile sensing applications. Using highly elastic and biocompatible Ecoflex silicone rubber as a substrate and abundant, inexpensive, and electrically conductive graphite as a functional filler, a 16×16 high-density flexible tactile sensor array is fabricated through composite thin film preparation, laser etching, and device assembly. This sensor array achieves efficient conversion of mechanical pressure into electrical signals through a Graphite / Ecoflex composite sensitive layer. Combined with a laser-etched ITO electrode array, its fabrication process is simple and controllable, with low cost. It possesses characteristics such as high-density sensing, high flexibility, wide pressure response range, and good biocompatibility, showing broad application prospects in the field of flexible electronic sensors.

[0018] To achieve the above objectives, the present invention is implemented through the following technical solution: This invention provides a method for fabricating a high-density flexible tactile sensor array. Using Graphite and Ecoflex silicone rubber as core materials, the method involves composite film fabrication, high-density ITO electrode array laser etching, device assembly, and performance optimization to obtain a 16×16 high-density flexible sensor array with tactile sensing function, enabling accurate detection of pressure signals and multi-scenario applications.

[0019] This invention provides the preparation steps for the above-mentioned Graphite / Ecoflex composite film, including: (1) Mix Ecoflex silicone rubber A and B in a mass ratio of 1:1 and stir thoroughly for 5 minutes until homogeneous; wherein, the Ecoflex silicone rubber is a two-component addition-type liquid silicone rubber; wherein the component of the A component is a vinyl-terminated polydimethylsiloxane main agent containing a platinum catalyst, and the component of the B component is a matching curing agent containing a hydrogen silicone oil crosslinking agent.

[0020] (2) Mix graphite and Ecoflex at a mass ratio of 50%, 55% or 60% respectively, and stir continuously for 15 minutes until a uniform composite graphite slurry is formed; (3) Select sandpaper that has been cleaned and dried with ethanol as a substrate, pour the composite graphite slurry onto the sandpaper substrate, and cover it with another layer of the same sandpaper. (4) Place the above assembly on a roller printer and move the scraper horizontally to form a uniform film between two layers of sandpaper. Then transfer it to a heating plate for curing. After curing, a Graphite / Ecoflex composite film is obtained.

[0021] Furthermore, the sandpaper grit in (3) is 220; the heating temperature in (4) is 80°C. o C, heating time is 2 hours.

[0022] A method for fabricating a high-density flexible tactile sensor array is provided for the aforementioned composite thin film. The fabrication steps include: (1) Design a 16×16 array of electrode patterns on the computer. (2) Place the ITO conductive film at the corresponding station of the laser etching equipment, start the marking operation, and obtain a 16×16 array of ITO electrodes; wherein the ITO conductive film is provided with a PET substrate; wherein, the PET polymer film is an insulating support substrate, and the ITO (indium tin oxide) conductive film layer is deposited only on a single side of it. PET is a non-conductive flexible carrier, and ITO is a functional conductive layer attached to PET. The two are an integral structure, and the ITO layer is the core electrode itself that realizes the acquisition of electrical signals.

[0023] (3) The Graphite / Ecoflex composite film is precisely bonded to the side of the two 16×16 array ITO electrodes away from the PET substrate, and a signal transmission line is led out. Combined with a signal acquisition module and a Bluetooth transmission module, a high-density flexible tactile sensor array is assembled.

[0024] Furthermore, the single array area of ​​the 16×16 ITO electrode array in (1) is 0.25 mm². 2 .

[0025] Specifically, the sensor array consists of a PET flexible substrate, a 16×16 ITO electrode array, and a Graphite / Ecoflex composite film. It is thin overall, highly flexible, and can be bent and deformed without being easily damaged.

[0026] The Graphite / Ecoflex composite film has a microstructure on its upper and lower surfaces that replicates the morphology of sandpaper. This microstructure is a multi-scale, non-uniformly distributed three-dimensional rough morphology of micro-protrusions and micro-grooves that is synchronously replicated on the upper and lower surfaces of the film. The core advantage of this structure is to improve the sensitivity and low-pressure detection capability of the sensor.

[0027] The mass fraction of graphite in the composite film is determined to be 50%. By adjusting the graphite content, the pressure response range and sensitivity of the sensor can be optimized. The core of the graphite content control lies in the precise control of the mass ratio of graphite to Ecoflex silicone rubber matrix to regulate the density and structure of the conductive permeation network inside the composite film. Films with 55% or 60% content are prone to unstable pressure response due to excessive viscosity.

[0028] Sixteen wires are led out from the top and bottom ITO electrode arrays, serving as the top and bottom electrodes respectively. A signal acquisition device is also provided, including a signal acquisition card connected by a ribbon cable and a Bluetooth receiver module, enabling real-time acquisition and wireless transmission of the sensor output signal. The top electrode, as the row scanning excitation end of the sensor array, is responsible for applying electrical signals row by row, transmitting external pressure, and acquiring the front-end piezoresistive change signal. The bottom electrode, as the column signal reading end of the sensor array, is responsible for acquiring the electrical signal at the corresponding point, achieving pressure spatial positioning, and providing a flat support substrate for the device. It pairs with the top electrode to form a complete sensing loop.

[0029] The core of the pressure detection sensor in this invention is the synergistic signal conversion based on the intrinsic piezoresistive effect of the Graphite / Ecoflex composite sensitive layer and the piezoresistive effect of the ITO electrode-composite film dual-interface contact, combined with the matrix addressing mechanism of the upper and lower orthogonal 16×16 ITO array electrodes, to realize the detection and distribution visualization of external pressure.

[0030] On the other hand, the present invention provides a tactile sensing application of a high-density flexible tactile sensor array, which can respond to external pressure and is applied to pressure distribution detection.

[0031] Furthermore, the fabricated high-density flexible tactile sensor array, fixed on the experimental platform, can realize real-time acquisition and wireless transmission of sensor output signals through the acquisition device. It can be used to detect the response to external pressure. The pressure magnitude can be determined by the magnitude of the electrical signal transmitted by each array in the sensor. Its pressure distribution is visualized as a color gradient change of "blue → green → yellow → red".

[0032] In the above scheme, Ecoflex, as a highly elastic silicon-based elastomer, possesses excellent flexibility, tensile resilience, and biocompatibility, making it an ideal choice for flexible sensing substrates. Graphite, as an abundant and inexpensive carbon-based material, has good conductivity and a layered structure, enabling efficient conversion of mechanical pressure into electrical signals. By combining graphite and Ecoflex to form a sensitive layer, and integrating it with a high-density electrode array design, this approach leverages the aforementioned advantages to optimize the fabrication process, improve interface compatibility, and expand the application scope of a high-density flexible tactile sensor array based on the Graphite / Ecoflex composite system. This results in a high-density flexible tactile sensor array that is simple to fabricate, stable in performance, and widely applicable.

[0033] The specific implementation method will be further described below with reference to the accompanying drawings.

[0034] Example 1: The preparation of a graphite / Ecoflex composite film includes the following steps: (1) Take 0.5g of Ecoflex A adhesive and 0.5g of Ecoflex B adhesive, put them in a beaker, and stir with a glass rod for 5 minutes until the mixture is uniform and transparent without obvious bubbles; (2) Weigh 1.0g of graphite powder, slowly add it to the above mixture, and stir continuously with a glass rod for 15 minutes to make the graphite particles uniformly dispersed and form a black viscous composite graphite slurry; (3) Select 220-mesh sandpaper, cut it into 5cm×5cm pieces, ultrasonically clean it in ethanol for 10 minutes, take it out and dry it in a 60℃ oven for 30 minutes; (4) Lay the dried sandpaper flat on a horizontal workbench, pour the composite graphite slurry evenly into the center of the sandpaper, quickly cover it with another sheet of sandpaper of the same size, and press lightly to spread the slurry evenly; (5) Place the above "sandpaper-slurry-sandpaper" structure on a roller printer, adjust the scraper height to 0.2mm, and move the scraper horizontally at a speed of 5mm / s to form a uniform film of slurry; (6) Transfer the film along with the sandpaper to a heating plate, set the temperature to 80℃, and heat for 2 hours to cure; after curing, allow it to cool naturally to room temperature, carefully peel off the upper and lower sandpaper layers to obtain a 5cm×5cm, approximately 0.2mm thick Graphite / Ecoflex composite sensitive film. The manufacturing process is as follows. Figure 1 As shown.

[0035] A method for fabricating a high-density flexible tactile sensor array: (1) Design a 16×16 electrode array pattern using AutoCAD software. The electrode unit size is 0.5mm×0.5mm, the electrode spacing is 0.167mm, and the lead-out ends are set at the edge of the array, with a total of 32 lead-out points; (2) Select an ITO conductive film (thickness 0.125mm) on a PET substrate, cut it to a size of 3m×3cm, wipe the surface with anhydrous ethanol to remove oil and impurities, and place it on the stage of a photolithography equipment after drying; (3) Import the designed electrode pattern into the photolithography equipment, and mark the ITO conductive film with red light; (4) After marking, immerse the ITO conductive film in deionized water for ultrasonic cleaning for 5min, and after drying, obtain a 16×16 ITO electrode array with clear electrode patterns and good conductivity. The fabrication process is as follows: Figure 1 As shown.

[0036] Example 2: A high-density flexible tactile sensor array was assembled by precisely bonding a Graphite / Ecoflex composite film to two 16×16 arrays of ITO electrodes, leading out signal transmission lines, and combining it with a signal acquisition module and a Bluetooth transmission module. Its structural schematic diagram and physical image are shown below. Figure 2 As shown.

[0037] Example 3: A tactile sensing application of a high-density flexible tactile sensor array, which can respond to external pressure, and the current changes with the external pressure under different external pressure conditions.

[0038] Figure 3 In the figure, 'a' represents the current change generated by a high-density flexible tactile sensor array using a 50% mass fraction Graphite / Ecoflex composite film under a pressure of 0.5N-1.5N.

[0039] Figure 3 In the figure, b represents the current change generated by a high-density flexible tactile sensor array using a 55% mass fraction Graphite / Ecoflex composite film under a pressure of 0.5N-1.5N.

[0040] Figure 3 In the figure, 'c' represents the current change generated by a high-density flexible tactile sensor array using a 60% mass fraction Graphite / Ecoflex composite film under a pressure of 0.5N-1.5N.

[0041] Figure 3 In this context, d represents the current change generated by a high-density flexible tactile sensor array using a 50% mass fraction Graphite / Ecoflex composite film under a pressure of 0.25N-2.0N.

[0042] Example 4: A tactile sensing application of a high-density flexible tactile sensor array is disclosed. The fabricated high-density flexible tactile sensor array is fixed on an experimental platform. Through a data acquisition device, the sensor output signal can be acquired in real time and wirelessly transmitted. It can be applied to pressure distribution detection, and the pressure distribution is visualized as a color gradient change of "blue → green → yellow → red".

[0043] Figure 4 For the pressure distribution visualization test of a high-density flexible tactile sensor array, the pressure distribution is displayed in real time through the acquisition software. The pressure concentration area is displayed in red, and the edge area is displayed in blue, clearly reflecting the pressure difference in different parts.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A high-density flexible tactile sensor array, characterized in that, include: A composite film, wherein the composite film contains graphite and Ecoflex silicone rubber; The composite film has ITO electrodes on both its upper and lower surfaces, and the ITO electrodes are different units divided by the ITO conductive film with a flexible substrate.

2. The high-density flexible tactile sensor array according to claim 1, characterized in that, The ITO electrodes are arranged in an array.

3. The high-density flexible tactile sensor array according to claim 1, characterized in that, The ITO electrode is connected to a corresponding wire, through which a sensing signal is output.

4. A method for fabricating a high-density flexible tactile sensor array according to any one of claims 1-3, characterized in that, include: Mix and stir different types of Ecoflex silicone rubber; Graphite and Ecoflex silicone rubber were mixed and stirred to form a uniform composite graphite slurry. A composite graphite paste is placed between two substrates; Two substrates are pressed together and the extruded graphite slurry is heated and cured to obtain a composite film. The ITO conductive film is segmented to obtain ITO electrodes; The ITO electrode is disposed on a flexible substrate; The ITO electrodes are bonded to the upper and lower surfaces of the composite film; A high-density flexible tactile sensor array is fabricated by leading wires out from the ITO electrode.

5. The preparation method according to claim 4, characterized in that, The substrate is a substrate with a non-flat surface having a regular or irregular shape, and the non-flat surface of the substrate is in contact with the composite graphite slurry.

6. The preparation method according to claim 4, characterized in that, The flexible substrate is a PET substrate.

7. The preparation method according to claim 4, characterized in that, The process of pressing the two substrates together includes: The substrate and the composite graphite slurry are used as an assembly, and the composite graphite slurry between the assemblies is squeezed by horizontal movement of a scraper.

8. The preparation method according to claim 4, characterized in that, The mass ratio of graphite to the mixed and stirred Ecoflex silicone rubber is 50%.

9. The preparation method according to claim 4, characterized in that, Methods for preparing ITO electrodes include: Obtain the electrode pattern; perform laser etching on the ITO conductive film according to the electrode pattern to obtain the ITO electrode.

10. The application of the high-density flexible tactile sensor array according to any one of claims 1-3, characterized in that, External pressure is applied to a high-density flexible tactile sensor array to detect the distribution of the applied external pressure.

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